Attendee inspect Smith and Wesson firearms at the National Rifle Association's (NRA) annual meeting, in Indianapolis, Indiana, U.S., April 28, 2019.
Smith & Wesson did not immediately respond to a request for comment.
Wednesday's lawsuits allege that Smith & Wesson knowingly advertised its weapons, including the M&P-model rifle used by Crimo, to appeal to "militaristic fantasies" of troubled young men.
"(Crimo) and other would-be mass shooters are highly susceptible to the disturbing promotional messages from Smith & Wesson," the lawsuits said.
They are asking the court to stop Smith & Wesson from the allegedly illegal marketing, including by putting age restrictions on social media content and removing military references, and to award unspecified monetary damages.